232 FLORA INDTCA, 2. ASSAM. The province of Assam is bounded by the Himalaya and Mishmi mountains on the north, and hy the Khasia and Naga hills on the south. It is a tropical valley continuous at its western extremity with the plains of Bengal, and gradually contracting to the eastward, till the mountains at last ap- proach so close together that no level country remains be- tween them. The width of the lower valley is about thirty miles; it is in general level, but low ranges of hills project occasionally fro;m both sides almost to the Brahmaputra, and isolated hillocks occur scattered here and there over the sur- face. The atmosphere is very humid, and dense fogs are frequent in winter. The rainy season lasts from May till October, and the rain-fall (about eighty inches at Gowahatti), though much less than on the mountains by which it is surrounded, is con- siderable. The climate is therefore on the whole equable, without excessive summer heat, and without great winter cold. Lower Assam is richly cultivated, but dense forest occu- pies the base of the hills on either side, as well as the hillocks which advance upon the plain. In Upper Assam there is but little cultivation, and much forest, which is often almost impervious from rank under- wood. Along the river the low alluvial plains, which at the junction of the Dihong are scarcely raised 350 feet above the level of the sea, are bare of trees, and covered with dense grass jungle. The mountains display a rich vegetation of the most tropical forms which India produces. Anonacea are numerous, several species of Myristicea occur, and the India- rubber fig forms large forests in some places. Calami and Plectocomia abound in the dense jungles, as well as other rare and interesting palms, belonging to the gcnoraiiwfcmi0, lAcuala, Arenga> *Jreca, Wallichia., etc. Oaks and ohcsnuts axe also characteristic types, as. are. Guttifem, Temstrwmia- ce&, Magnolwcea, Saurauja, and tree-ferns.